If you go to Cydia, on the main page (left column), there is a box titled "Root Password How-To." When you select that, the second item down is a box titled "Mobile Terminal Package." Click on that and you'll get the normal Cydia options to download it (free).
Or, at least that's how I got Mobile Terminal on my iPad with iOS 4.2.1. It does say that it's the latest version (for iOS 4 to 4.3.1). Works on my iPad...
Marilyn
P.S. Oh, and it wouldn't hurt to also change your mobile password on the iPad as well as the root.